The present invention relates to a load port, a semiconductor manufacturing apparatus, a semiconductor manufacturing method, and a method of detecting a wafer adapter.
In a semiconductor manufacturing factory, a wide variety of products are produced in respective limited amounts. To this end, semiconductor wafers having various different sizes are conveyed on a single production line on a lot-by-lot basis. Processing devices arranged on the production line perform different processing operations on the wafers, depending on the sizes of the wafers. To properly transfer and process the wafers, it is necessary to detect the sizes of the wafers efficiently.
Generally, semiconductor wafers are contained in an open-type cassette called an open cassette, and carried to a manufacturing apparatus that performs processing operations, such as etching, CVD (Chemical Vapor Deposition), and PVD (Physical Vapor Deposition). The open cassette is capable of containing a plurality of semiconductor wafers. Within the open cassette, wafers are stacked at a predetermined interval. Semiconductor wafers are increasing in size with the advance in semiconductor manufacturing technology. Recently, 8-inch and 12-inch semiconductor wafers are used. This leads to an increase in the size of cassettes.
Although the cassettes have horizontal sizes dependent on the diameters of wafers, they have predetermined vertical sizes (heights). For instance, cassettes for accommodating 4-inch, 5-inch, and 6-inch semiconductor wafers have a vertical size (height) large enough to accommodate twenty-five wafers at a pitch of 4.76 mm. A cassette for accommodating 8-inch semiconductor wafers has a vertical size (height) large enough to accommodate twenty-five wafers at a pitch of 6.35 mm. A cassette for accommodating 12-inch semiconductor wafers has a vertical size (height) large enough to accommodate twenty-five wafers at a pitch of 10 mm.
In a general semiconductor production line, a closed-type container is used. The closed-type container includes an SMIF (Standard Mechanical Interface) pod 20 shown in FIG. 1, and a FOUP (Front Opening Unified Pod) 21 shown in FIG. 2. The SMIF pod 20 and the FOUP 21 transfer a plurality of semiconductor wafers to a manufacturing apparatus while maintaining their inner spaces for containing the wafers at a high level of cleanliness.
The SMIF pod 20 is a casing for containing a wafer cassette. On the other hand, the FOUP 21 has an inner wall formed with a shelf 22 for holding a plurality of semiconductor wafers. The shelf 22 has a plurality of layers of slots 22a. Each slot 22a holds one semiconductor wafer. The FOUP 21 compliant with SEMI (Semiconductor Equipment and Materials International) standards is configured such that semiconductor wafers can be taken in and out by opening a lid 23 arranged in the front of the FOUP 21.
FIG. 3 is a plan view of a conventional semiconductor manufacturing apparatus 30 which transfers semiconductor wafers W by using the FOUP 21. Two load ports 31, 32 are arranged on the front of the apparatus 30 (on a right-hand side as viewed in the figure) in a manner adjacent to each other. The FOUP 21 is placed on each of the load ports 31, 32. The load ports 31, 32 are constructed in accordance with the SEMI standards. Each load port includes an opener 33 for opening and closing the lid 23 of the FOUP 21. When the opener 33 opens the lid 23 of the FOUP 21, a transfer robot 34 carries wafers W from the FOUP 21 into the semiconductor manufacturing apparatus 30.
The semiconductor manufacturing apparatus 30 is capable of processing 8-inch semiconductor wafers and 12-inch semiconductor wafers. More specifically, the apparatus 30 is based on equipment for processing 12-inch (300-mm) wafers and modified such that it can deal with 8-inch (200-mm) wafers as well. Wafers W are transferred between the apparatus 30 and the FOUP 21. The FOUP 21, which is a transfer pod for transferring 12-inch wafers, cannot hold 8-inch wafers W. To overcome this problem, a wafer adapter 25 shown in FIG. 4 is mounted in the FOUP 21 to thereby enable the FOUP 21 to contain 8-inch wafers W. The wafer adapter 25 has a side wall 26 which is formed to fit on peripheries of 8-inch wafers W. The side wall 26 is formed with a plurality of layers of slots 26a. Each slot 26a holds one wafer W.
It should be noted that a pitch at which 8-inch wafers W are accommodated is different from a pitch at which 12-inch wafers W are accommodated. Further, in the FOUP 21, each 12-inch wafer W set on the shelf 22, and each 8-inch wafer W set by using the wafer adapter 25 are arranged such that end portions thereof toward the apparatus 30 are in the same position, and hence the position of the center of the 8-inch wafer is different from that of the center of the 12-inch wafer. The transfer robot 34 carries a wafer W on a hand 34a thereof. To transfer the wafer W accurately, the transfer robot 34 is required to recognize the size of the wafer and cause the center of the wafer W to coincide with the center of the hand 34a. Therefore, it is necessary to recognize the size of the wafer.
The semiconductor manufacturing apparatus 30 includes a charge coupled device (CCD) camera 36, and a controller 37 for controlling the CCD camera 36. Whether or not the wafer adapter 25 is mounted in the FOUP 21 is detected based on data of an image thereof taken by the CCD camera 36. The apparatus 30 recognizes the size of a wafer to be processed according to a result of the detection.
However, to detect the wafer adapter 25 by the CCD camera 36, it is necessary to take into account the color of the FOUP 21, and brightness around the FOUP 21. Further, a location for setting the CCD camera 36 is restricted by the SEMI standards. To meet these conditions for detecting the wafer adapter 25, the apparatus necessarily has a complicated construction.
Since the load ports 31, 32 are constructed in accordance with the SEMI standards, it is impossible to provide a space for arranging the CCD camera 36 and the controller 37 in the load ports 31, 32. For this reason, the CCD camera 36 and the controller 37 are arranged on an opposite side of (rearward of) the load ports 31, 32 with respect to the transfer robot 34. This arrangement causes an increase in the floor area of the semiconductor manufacturing apparatus 30, resulting in the increased size thereof.